Exhaust pipe structure

ABSTRACT

An exhaust pipe structure has: an exhaust pipe through which exhaust from an engine flows; a communicating portion that is formed in a lower surface side of the exhaust pipe further toward a downstream side, in a direction of flow of the exhaust, than a catalyst device provided at the exhaust pipe, and that communicates an interior and an exterior of the exhaust pipe; and a porous body that is disposed at the communicating portion and that leads moisture, which is at the interior of the exhaust pipe, to the exterior of the exhaust pipe by capillary action.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese Patent Application No. 2016-165882 filed Aug. 26, 2016, the disclosure of which is incorporated by reference herein.

BACKGROUND Technical Field

The present invention relates to an exhaust pipe structure.

Related Art

Japanese Patent Application Laid-Open (JP-A) No. H10-131745 discloses an exhaust pipe structure for a combustion heater in which a drain hole is formed in the lowermost point of an exhaust pipe, and in which, due to moisture, which is generated by water vapor that is within exhaust gas condensing, being discharged-out from the drain hole, it is difficult for the condensed moisture to remain within the exhaust pipe.

In the above-described technique, a drain hole is merely formed in the exhaust pipe, and the drain hole communicates the interior and the exterior of the exhaust pipe. Therefore, there is the concern that exhaust gas also will be discharged-out from the drain hole.

SUMMARY

In view of the above-described circumstances, the present invention provides an exhaust pipe structure in which moisture can be discharged from a communicating portion that communicates the interior and exterior of an exhaust pipe, and in which discharging of exhaust gas can be suppressed.

An exhaust pipe structure of a first aspect of the present invention has: an exhaust pipe through which exhaust from an engine flows; a communicating portion that is formed in a lower surface side of the exhaust pipe further toward a downstream side, in a direction of flow of the exhaust, than a catalyst device provided at the exhaust pipe, and that communicates an interior and an exterior of the exhaust pipe; and a porous body that is disposed at the communicating portion and that leads moisture, which is at the interior of the exhaust pipe, to the exterior of the exhaust pipe by capillary action.

In this exhaust pipe structure, the communicating portion is formed further toward the downstream side, in the direction of the flow of the exhaust, than the catalyst device. The porous body is disposed at the communicating portion. By capillary action, the porous body leads moisture, which is at the interior of the exhaust pipe, to the exterior of the exhaust pipe. Therefore, moisture that is at the interior of the exhaust pipe can be discharged through the communicating portion to the exterior of the exhaust pipe. Because the porous body is disposed at the communicating portion, exhaust being discharged-out to the exterior of the exhaust pipe from the communicating portion can be suppressed.

In an exhaust pipe structure of a second aspect, in the first aspect, the communicating portion has a through-hole that passes-through a pipe wall of the exhaust pipe, and the exhaust pipe structure has a supporting member that supports the porous body from an outer side of the exhaust pipe.

For the communicating portion, it suffices to form a through-hole that passes-through the pipe wall of the exhaust pipe, and the structure of the communicating portion is simple. Further, because the porous body is supported by the supporting member from the outer side of the exhaust pipe, falling-out of the porous body can be suppressed.

In an exhaust pipe structure of a third aspect, in the first aspect, the communicating portion has a through-hole that passes-through a pipe wall of the exhaust pipe, and a projecting tube that projects-out into the interior of the exhaust pipe at a position of the through-hole.

Because the communicating portion has the through-hole and the projecting tube, the porous body can be held by either one of, or both of, the through-hole and the projecting tube. Further, the amount of exhaust that is discharged-out from the interior of the exhaust pipe to the exterior can be adjusted in accordance with the length and/or the inner diameter of the projecting tube.

In an exhaust pipe structure of a fourth aspect, in the third aspect, the porous body has an in-tube portion that is positioned at an interior of the projecting tube, and an extension portion that extends downward from the in-tube portion at the interior of the exhaust pipe.

The extension portion of the porous body extends downward from the projecting tube, at the interior of the exhaust pipe. Therefore, as compared with a porous body that does not have an extension portion, moisture that is at an even lower position can be discharged-out to the exterior of the exhaust pipe by the capillary action of the porous body.

In an exhaust pipe structure of a fifth aspect, in the first aspect, the exhaust pipe has plural connected tubes that are connected to one another, and at least a portion of a gap between the plural connected tubes is the communicating portion.

The communicating portion can be formed as at least a portion of the gap between plural connected pipes. Therefore, there is no need to form a through-hole or the like in the exhaust pipe in order to form the communicating portion, and simplification of the structure can be devised.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein:

FIG. 1 is a side view showing the structure of an exhaust pipe to which an exhaust pipe structure of a first embodiment of the present invention is applied;

FIG. 2 is a cross-sectional view showing, partially and in an enlarged manner, the exhaust pipe to which the exhaust pipe structure of the first embodiment of the present invention is applied;

FIG. 3 is a cross-sectional view showing, partially and in an enlarged manner, the exhaust pipe to which an exhaust pipe structure of a second embodiment of the present invention is applied;

FIG. 4 is a cross-sectional view showing, partially and in an enlarged manner, the exhaust pipe to which an exhaust pipe structure of a third embodiment of the present invention is applied;

FIG. 5 is a cross-sectional view showing, partially and in an enlarged manner, the exhaust pipe to which an exhaust pipe structure of a fourth embodiment of the present invention is applied;

FIG. 6 is a cross-sectional view showing, partially and in an enlarged manner, the exhaust pipe to which an exhaust pipe structure of a fifth embodiment of the present invention is applied;

FIG. 7 is a side view showing the structure of the exhaust pipe to which an exhaust pipe structure of a sixth embodiment of the present invention is applied; and

FIG. 8 is a cross-sectional view showing, partially and in an enlarged manner, the exhaust pipe to which the exhaust pipe structure of the sixth embodiment of the present invention is applied.

DETAILED DESCRIPTION

An exhaust pipe, to which an exhaust pipe structure 12 of a first embodiment is applied, is described with reference to the drawings.

As shown in FIG. 1, one end 14A in the longitudinal direction of an exhaust pipe 14 is connected to an unillustrated engine of a vehicle. Exhaust that is generated at the engine flows through the exhaust pipe 14, and is discharged to the exterior from another end 14B in the longitudinal direction of the exhaust pipe 14. In the drawings, the direction of the flow of the exhaust is shown by arrows F1. When merely “upstream” and “downstream” are used hereinafter, they mean the upstream and the downstream of the flow of the exhaust, respectively.

In the present embodiment, the exhaust pipe 14 is formed overall in the shape of a cylinder, and the cross-sectional shape of the exhaust pipe 14 is circular. In the drawings, the center of the exhaust pipe 14 is shown by central line CL.

The exhaust pipe 14 may be bent at predetermined positions as shown in FIG. 1, in accordance with the structure of the vehicle, the arrangement of the various members of the vehicle, or the like. Further, the exhaust pipe 14 is a structure in which plural connected pipes 14C are connected to one another by connecting portions 16 (couplings).

A catalyst device 18 is provided midway along the exhaust pipe 14. When exhaust passes-through the catalyst device 18, specific substances within the exhaust are removed, and the exhaust is purified.

A through-hole 22 is formed in the exhaust pipe 14 in the lower surface side thereof, i.e., further toward the lower side than the central line CL, at the downstream side of the catalyst device 18. In a structure in which the exhaust pipe 14 is bent at predetermined positions that are further toward the downstream side than the catalyst device 18, portions 14P, which are at relatively high positions (are positioned at the upper side), and a portion 14Q, which is at a relatively low position (is positioned at the lower side), exist at the exhaust pipe 14. In this case, the through-hole 22 is formed in the portion 14Q that is positioned relatively at the lower side.

In the first embodiment, the through-hole 22 has an inner diameter 22N that is smaller than an inner diameter 14N of the exhaust pipe 14, and is a hole that passes-through a pipe wall 14W of the exhaust pipe 14 in the thickness direction. The interior and the exterior of the exhaust pipe 14 are communicated in the thickness direction of the exhaust pipe 14 by the through-hole 22. The through-hole 22 is an example of a communicating portion 20.

A fiber material 24 is disposed in the through-hole 22. The fiber material 24 is formed of glass wool, ceramic wool, stainless steel wool, rock wool, carbon fibers, or the like. The fiber material 24 has the property of having wettability that is high to the extent that, when moisture LW contacts a portion of the fiber material 24, the moisture LW wets the fiber material 24 and spreads therein due to capillary action. In other words, the fiber material 24 has the property that the contact angle of the moisture LW is small.

Moreover, the fiber material 24 is heat-resistant to the extent that, even if heat of the exhaust is applied thereto, the above-described property and the shape of the fiber material 24 substantially do not change. For example, in a structure in which a binder is coated on the fibers that structure the fiber material 24, the property and the shape of the fiber material 24 can be maintained stably.

In the first embodiment, the fiber material 24 is press-fit into the through-hole 22, and the fiber material 24 that has been contracted tightly contacts the inner surface of the through-hole 22. When exhaust flows through the exhaust pipe 14, the pressure at the interior of the exhaust pipe 14 is high, but because the fiber material 24 tightly contacts the inner surface of the through-hole 22, the fiber material 24 falling-out is suppressed. As shown in FIG. 2, when employing a structure in which the fiber material 24 is spread-out further at the inner side of the exhaust pipe 14 than the through-hole 22, a broad portion 24H spreads-out further than the inner diameter 22N of the through-hole 22, and therefore, falling-out of the fiber material 24 from the through-hole 22 can be suppressed more effectively.

Operation of the first embodiment is described next.

There are cases in which water vapor, which is contained in the exhaust that flows through the exhaust pipe 14, condenses (liquefies) due to a drop in temperature of the exhaust that is in the midst of flowing through the exhaust pipe 14, or the like, and the moisture LW is generated within the exhaust pipe 14.

The through-hole 22 is formed in the exhaust pipe 14, and the interior and the exterior of the exhaust pipe 14 are communicated thereby. Further, the fiber material 24 is disposed in the through-hole 22. Accordingly, the moisture LW within the exhaust pipe 14 seeps into the fiber material 24 due to the capillary action of the fiber material 24, and is discharged to the exterior of the exhaust pipe 14.

The through-hole 22 communicates the interior and the exterior of the exhaust pipe 14. However, because the fiber material 24 is provided thereat, the exhaust that is within the exhaust pipe 14 passing-through the through-hole 22 and being discharged to the exterior of the exhaust pipe 14 is suppressed. Phenomena, such as the generation of abnormal noise due to exhaust passing through the through-hole 22, and the like, also can be suppressed.

In particular, in a state in which the moisture LW has seeped into the fiber material 24 due to capillary action, the pores (the spaces between the fibers) of the fiber material 24 are blocked-up by the moisture LW. Therefore, the effect of suppressing exhaust passing-through the pores of the fiber material 24 and flowing-out to the exterior of the exhaust pipe 14 is strong.

In a case in which foreign matter such as soot or the like is contained in the exhaust, the fiber material 24 acts as a filter, and therefore, foreign matter passing-through the through-hole 22 is suppressed. For example, even in a case in which foreign matter exists within the moisture LW, the moisture can be filtered by the fiber material 24.

A second embodiment is described next. In the second embodiment, elements, members and the like that are similar to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Further, in the second embodiment, the overall structure of the exhaust pipe is similar to the first embodiment, and therefore, illustration thereof is omitted.

As shown in FIG. 3, an exhaust pipe structure 32 of the second embodiment has punched plates 36S, 36U.

The punched plates 36S, 36U are members in which plural punch holes 38 are formed in plate members, which can cover the through-hole 22, in the thickness direction of the plate members. An inner diameter 38N of the punch holes 38 is smaller than the inner diameter 22N of the through-hole 22. The punched plate 36S supports the fiber material 24 from the outer side of the exhaust pipe 14, i.e., from the lower side of the fiber material 24, and is an example of a supporting member 34.

The exhaust pipe structure 32 has not only the punched plate 36S that is positioned at the lower side of the exhaust pipe 14, but also the punched plate 36U that is positioned at the inner side of the exhaust pipe 14, i.e., at the upper side of the fiber material 24. The fiber material 24 is held so as to be nipped-in from above and below by the two punched plates 36S, 36U.

In the exhaust pipe structure 32 of the second embodiment, because the punched plate 36S supports the fiber material 24, the effect of suppressing falling-out of the fiber material 24 from the through-hole 22 is strong as compared with a structure that does not have the punched plate 36S.

In addition, because the punched plate 36U is provided at the upper side of the fiber material 24 as well, the fiber material 24 inadvertently moving from the through-hole 22 toward the inner side of the exhaust pipe 14 also can be suppressed.

Because the punch holes 38 are formed in the punched plates 36S, 36U, movement of moisture from the interior to the exterior of the exhaust pipe 14 is not affected.

In the exhaust pipe structure 32 of the second embodiment, a wire mesh can be used as the supporting member 34 instead of or together with the punched plate 36S. A wire mesh is a member in which wire materials are interwoven in the form of a mesh (the form of a lattice, the form of a honeycomb, or the like). The gaps between the interwoven mesh materials substantially function similarly to the punch holes of the punched plates, and moisture can pass therethrough.

A third embodiment is described next. In the third embodiment, elements, members and the like that are similar to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Further, in the third embodiment, the overall structure of the exhaust pipe is similar to the first embodiment, and therefore, illustration thereof is omitted.

As shown in FIG. 4, an exhaust pipe structure 42 of a third embodiment has a projecting tube 44. The projecting tube 44 is a tubular (pipe-shaped) member and has length 44L that is shorter than the inner diameter 14N of the exhaust pipe 14, and an outer diameter 44G that is that is the same extent as the inner diameter 22N of the through-hole 22.

One end portion 44A (the lower end portion) side of the projecting tube 44 is fixed to the exhaust pipe 14 at the interior of the through-hole 22, and another end portion 44B (the upper end portion) of the projecting tube 44 is positioned at the interior of the exhaust pipe 14. Namely, the projecting tube 44 projects-out into the interior of the exhaust pipe 14 at the position of the through-hole 22. Further, the communicating portion 20 is a structure having the through-hole 22 and the projecting tube 44 that is at the inner side thereof.

Note that there may be a structure in which an inner diameter 44N of the projecting tube 44 is formed to be the same extent as the inner diameter 22N of the through-hole 22, and the projecting tube 44 is fixed to the inner peripheral surface of the exhaust pipe 14. In this structure, the communicating portion 20 is structured by the inner side of the projecting tube 44 and the through-hole 22 being made to be a continuous shape.

In the exhaust pipe structure 42 of the third embodiment, the fiber material 24 is press-fit in and held at the interior of the projecting tube 44. The entire fiber material 24 is an in-tube portion 46 that is positioned at the interior of the projecting tube 44. One end portion 24A of the fiber material 24 is at substantially the same height as the one end portion 44A of the projecting tube 44. Similarly, another end portion 24B of the fiber material 24 is at the same height as the other end portion 44B of the projecting tube 44.

In the exhaust pipe structure 42 of the third embodiment, of the moisture that is at the interior of the exhaust pipe 14, the moisture LW that is further upward than the other end portion 44B (the upper end portion) contacts the fiber material 24. The contacting moisture LW is discharged to the exterior of the exhaust pipe 14 by the capillary action of the fiber material 24.

In the exhaust pipe structure 42 of the third embodiment, the length 44L and the inner diameter 44N of the projecting tube 44 can be adjusted. By adjusting the length 44L and the inner diameter 44N of the projecting tube 44, the discharged amount of the exhaust that is discharged from the interior to the exterior of the exhaust pipe 14 through the communicating portion 20 can be adjusted. For example, if the length 44L of the projecting tube 44 is made to be long or the inner diameter 44N is made to be small, the flow path resistance of the interior of the projecting tube 44 increases, and therefore, the amount of gas that is discharged-out through the through-hole 22 can be made to be smaller.

Note that, in the third embodiment, in the example shown in FIG. 4, the length of the fiber material 24 is the same as the length from the one end portion 44A of the projecting tube 44 (the outer periphery of the exhaust pipe 14) to the other end portion 44B of the projecting tube 44. However, the length of the fiber material 24 does not have to be the same as the length of the projecting tube 44, and the fiber material 24 may jut-out further upward and/or downward than the projecting tube 44.

A fourth embodiment is described next. In the fourth embodiment, elements, members and the like that are similar to those of the first embodiment or the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Further, in the fourth embodiment, the overall structure of the exhaust pipe is similar to the first embodiment, and therefore, illustration thereof is omitted.

As shown in FIG. 5, in an exhaust pipe structure 52 of the fourth embodiment, a fiber material 54 has an extension portion 56 in addition to the in-tube portion 46. The extension portion 56 is continuous from the in-tube portion 46 toward the interior of the exhaust pipe 14, and extends downward. Another end portion 54B of the fiber material 54 either contacts the inner peripheral surface of the exhaust pipe 14, or is at a position that is near to the inner peripheral surface. In contrast, one end portion 54A of the fiber material 54 is at the same height as the one end portion 44A of the projecting tube 44, i.e., the outer peripheral surface of the exhaust pipe 14. Accordingly, the other end portion 54B of the fiber material 54 is at a higher position than the one end portion 54A.

In the exhaust pipe structure 52 of the fourth embodiment, the extension portion 56 of the fiber material 54 extends downward at the exterior of the projecting tube 44 in this way. Accordingly, as compared with a fiber material that does not have the extension portion 56, the moisture LW that is at a lower position can be led to the exterior of the exhaust pipe 14 and discharged-out by the capillary action of the fiber material 54.

Moreover, the other end portion 54B of the fiber material 54 is at a higher position than the one end portion 54A. Accordingly, moisture is moved from the other end portion 54B side (the extension portion 56) to the one end portion 54A side (the in-tube portion 46) not only by the capillary action of the fiber material 54, but also by the principle of siphoning. Moisture within the exhaust pipe 14 can thereby be discharged to the exterior of the exhaust pipe 14.

A fifth embodiment is described next. In the fifth embodiment, elements, members and the like that are similar to those of the first embodiment through the fourth embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Further, in the fifth embodiment, the overall structure of the exhaust pipe is similar to the first embodiment, and therefore, illustration thereof is omitted.

As shown in FIG. 6, in an exhaust pipe structure 62 of the fifth embodiment, an extending-out tube 64 extends-out from the upper portion of the projecting tube 44. The extending-out tube 64 has a first extending-out portion 64P, which extends-out in the lateral direction (toward the downstream side in the example of FIG. 6) from the projecting tube 44, and a second extending-out portion 64Q, which extends-out downward from an end portion of this first extending-out portion 64P. A tube member 66 that is integral and is substantially upside-down U-shaped is formed by the projecting tube 44 and the extending-out tube 64.

Accordingly, in the exhaust pipe structure 62 of the fifth embodiment, in the state in which the liquid level of the moisture LW is further upward than a lower end portion 66B of the second extending-out portion 64Q of the tube member 66, gravity that acts on the moisture LW works as force that pushes the moisture LW in from the lower end portion 66B into the tube member 66. Further, when exhaust flows through the exhaust pipe 14 interior, the pressure of the exhaust that acts on the moisture LW also works as force that pushes the moisture LW in from the lower end portion 66B into the tube member 66.

Therefore, in the exhaust pipe structure 62 of the fifth embodiment, the moisture LW flows in the interior of the tube member 66 due to capillary action and the principle of siphoning, and the effect of discharging moisture out to the exterior of the exhaust pipe 14 is strong.

A sixth embodiment is described next. In the sixth embodiment, elements, members and the like that are similar to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Further, in the sixth embodiment, the overall structure of the exhaust pipe is similar to the first embodiment, and therefore, illustration thereof is omitted.

As shown in FIG. 8, in an exhaust pipe structure 72 of the sixth embodiment, the plural connected pipes 14C are connected by the connecting portion 16, and the communicating portion 20 is formed at a gap 14D between the connected pipes 14C. Concretely, each of the two connected pipes 14C has a flange portion 74 that is annular at the connecting portion 16. The flange portions 74 are fastened together by using fastening members such as bolts 76 or the like, and the connected pipes 14C are connected to one another. In the sixth embodiment, the position of the gap 14D (the flange portions 74) is at the portion 14Q that is positioned relatively toward the lower side at the exhaust pipe 14 as shown in FIG. 7.

The fiber material 24 is disposed between the flange portions 74. The fiber material 24 is formed in an annular shape in correspondence with the flange portions 74 that are annular, and, in the peripheral direction, blocks the gap 14D between the flange portions 74.

In this way, in the sixth embodiment, the communicating portion 20 is formed by effectively utilizing the gap 14D between the connected pipes 14C. Because the communicating portion 20 can be formed without forming a through-hole in the exhaust pipe 14, i.e., in each of the plural connected pipes 14C, simplification of the structure of the exhaust pipe structure 72 can be devised.

In the sixth embodiment, the two flange portions 74 are fastened by fastening members such as the bolts 76 or the like. Because the fiber material 24 can be compressed and held by the fastening force of these fastening members, falling-out of the fiber material 24 can be suppressed.

Note that, in the above-described respective embodiments, the fiber material is used as an example of the porous body, but, other than this, for example, a sintered body in which powder solids are sintered and fixed together, or active carbon, zeolite, non-woven cloth, or the like may be used.

In the above-described embodiments, the communicating portion 20 is at the lower surface side of the exhaust pipe 14, i.e., is further toward the lower side than the central line CL. Accordingly, as compared with a structure which the communicating portion 20 is formed at the upper surface side of the exhaust pipe 14, it is easy for the moisture LW, which has collected at the lower side at the interior of the exhaust pipe 14, to be discharged-out to the exterior of the exhaust pipe 14.

In the above-described embodiments, the through-hole 22, the projecting tube 44 and the gap 14D are given as examples of the communicating portion 20. At the exhaust pipe 14, there are cases in which, for example, the flow path of the exhaust branches-off, and a shaft coupling or the like is provided at the portion of branching. In this case, the communicating portion can be formed at the shaft coupling.

It suffices for the position at which the communicating portion is provided to be at the exhaust pipe at further toward the downstream side than the catalyst device 18. In the examples shown in FIG. 1 and FIG. 7, a muffler 78 is provided, as a portion of the exhaust pipe, further toward the downstream side than the catalyst device 18. Further, depending on the type of the exhaust pipe 14, there are cases in which the muffler 78 is at the portion 14Q that is positioned relatively toward the lower side. In this case, a structure in which the communicating portion 20 is provided at the muffler 78 may be employed. 

What is claimed is:
 1. An exhaust pipe structure comprising: an exhaust pipe through which exhaust from an engine flows; a communicating portion that is formed in a lower surface side of the exhaust pipe further toward a downstream side, in a direction of flow of the exhaust, than a catalyst device provided at the exhaust pipe, and that communicates an interior and an exterior of the exhaust pipe; and a porous body that is disposed at the communicating portion and that leads moisture, which is at the interior of the exhaust pipe, to the exterior of the exhaust pipe by capillary action.
 2. The exhaust pipe structure of claim 1, wherein the communicating portion has a through-hole that passes-through a pipe wall of the exhaust pipe, and the porous body is press-fit into the through-hole and fits tightly to an inner surface of the through-hole.
 3. The exhaust pipe structure of claim 2, wherein the porous body has, at an inner side of the exhaust pipe, a broad portion whose inner diameter is wider than an inner diameter of the through-hole.
 4. The exhaust pipe structure of claim 1, wherein the communicating portion has a through-hole that passes-through a pipe wall of the exhaust pipe, and the exhaust pipe structure comprises a supporting member that supports the porous body from an outer side of the exhaust pipe.
 5. The exhaust pipe structure of claim 4, further comprising a second supporting member that supports the porous body from an inner side of the exhaust pipe.
 6. The exhaust pipe structure of claim 1, wherein the communicating portion has a through-hole that passes-through a pipe wall of the exhaust pipe, and a projecting tube that projects-out into the interior of the exhaust pipe at a position of the through-hole.
 7. The exhaust pipe structure of claim 6, wherein a lower end portion of the porous body and a lower end portion of the projecting tube are at substantially a same height, an upper end portion of the porous body and an upper end portion of the projecting tube are at substantially a same height, and the entire of the porous body is positioned at an interior of the projecting tube.
 8. The exhaust pipe structure of claim 6, wherein the porous body has an in-tube portion that is positioned at an interior of the projecting tube, and an extension portion that extends downward from the in-tube portion at the interior of the exhaust pipe.
 9. The exhaust pipe structure of claim 8, wherein a lower end portion of the porous body at the in-tube portion and a lower end portion of the projecting tube are at substantially a same height, and a lower end portion of the porous body at the extension portion is at a higher position than the lower end portion of the porous body at the in-tube portion.
 10. The exhaust pipe structure of claim 6, further comprising: an extending-out tube that extends-out from the projecting tube, wherein the extending-out tube has a first extending-out portion that extends-out in a lateral direction from the projecting tube, and a second extending-out portion that extends-out downward from an end portion of the first extending-out portion, and the projecting tube and the extending-out tube form a tube member that is integral and is substantially upside-down U-shaped.
 11. The exhaust pipe structure of claim 1, wherein the exhaust pipe has a plurality of connected tubes that are connected to one another, and at least a portion of a gap between the plurality of connected tubes is the communicating portion. 